Extended Abstract (420K)6.4
Exploration of Subgrid Routing Responses in Noah router
David J. Gochis, NCAR, Boulder, CO; and F. Chen
At increasingly finer grid scales (e.g. < 1 km) lateral redistribution of surface and subsurface water become increasingly important in local water budgets. In recognition of this, grid-based overland flow and saturated subsurface routing schemes have recently been implemented into an offline gridded version of the Noah surface-vegetation-atmosphere transfer (SVAT) model along with an aggreagation/disaggregation algorithm. Overland flow routing is performed via a two-dimensional diffusive wave for overland flow. Saturated subsurface routing is performed via a finite-difference application of the Dupuit-Forchheimer assumptions. One primary motivation for this work was to evaluate the effect of infiltration excess redistribution on land surface fluxes and associated soil moisture heterogeneity. The model is tested using the rich dataset from the Coupled-Atmosphere-Surface-Exchange-Study (CASES), which includes high-resolution (4 km) distributed rainfall estimates from polarimetric radar as well as continuous local measurements of soil temperature, streamflow and land surface fluxes. A series of simulations using different sub-grid horizonatal resolutions have been made to explore the scale effects of high-resolution surface features on runoff production and land surface fluxes. Preliminary results confirm other studies which have found the runoff production is increased and that local variations in terrain become more important at finer horizontal resolutions.
Session 6, Scale Issues in Weather and Climate Modeling, Including Downscaling and Validation (Room 6E)
Thursday, 15 January 2004, 1:30 PM-5:00 PM, Room 6E
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